Hydraulic door closer



Nov. 13, 19 56 c. s. COMEY ET AL HYDRAULIC DOOR CLOSER Filed July 26, 1951 WAR V/QW? mfim .4! 1.. all

s 5 i 7: NMAa a was; r m M :mc r ink m w .1 W 6 United States Patent HYDRAULIC DOOR CLOSER Charles S. Comey, Ferndale, and Millard Francis Saxton This invention relates to a door closer and more particularly to hydraulic and pneumatic door closers.

One of the difliculties with hydraulic door closers of the inexpensive type usually used on storm doors and screen doors is that, after a relatively short period of use, they develop leaks. It is believed that leakage in this type of door closer is due primarily to the building up within the hydraulic system, at least momentarily, of very high pressures, pressures very much in excess of those for which these units are primarily designed. A door closer of this type usually comprises a cylinder having a piston axially movable therein and a piston rod associated with the piston and extending out through one end of the cylinder. The cylinder is filled with hydraulic fluid and the piston is associated with a valve arrangement which permits the fluid to flow freely from one side of the piston to the other and more slowly in the opposite direction.

With this arrangement it will be seen that on one side of the piston the volume of the cylinder which can be occupied by the hydraulic fluid is diminished by the displacement of the piston rod while the volume of the cylinder on the opposite side of the piston comprises the actual volume of the cylinder. Therefore, as the piston moves axially of the cylinder, it will be appreciated that the change in volume on one side of the piston is not commensurate with the change in volume on the other side of the piston. Consequently, very high pressures are built up, at least momentarily, on either one side of the piston or the other; and it is believed that this build up of tremendous pressures accounts for the leakage associated with inexpensive door closers of this type.

In the case of pneumatic door closers, the primary source of difliculty has usually been the inability to adjust the device such that the door will close at a desired rate and at the same time with suflicient force to latch. The rate at which the door closes is usually controlled by varying the size of the air escape orifice. Usually it is desired to have the door close rather rapidly through a major portion of its travel and slowly during the end portion of its movement but with suflicient force to latch. With pneumatic closers with which we are familiar it is next to impossible to obtain the desired closing movement of the door. If the air escape orifice is made large enough to enable the door to latch, the door closes too rapidly; it does not bounce back and close slowly near the end of its movement. On the other hand, if the orifice is adjusted such that the door closes slowly, then it doesnt swing shut with suflicient force to latch.

It is an object of this invention to provide a hydraulic or pneumatic door closer of the inexpensive variety which is constructed so that in operation it is not subjected to high pressure and therefore not apt to leak, and at the same time a door closer which can be adjusted to produce the desired closing action.

More specifically, the invention contemplates a fluid operated door closer of the low-pressure type provided 2,770,003 Patented Nov. 13, 1956 with means for compensating for the ditferent rates at which the volume on each side of the piston varies as the piston moves axially of the cylinder. The means employed for compensating for the different rates of change in volume is preferably in the form of a springbiased diaphragm positioned such as to increase or decrease the etfective volume of the cylinder on one side of the piston and thereby accommodate a greater or lesser amount of hydraulic fluid displaced by the piston. The diaphragm also serves as a cushion for relieving the normally high pressures which would otherwise be developed.

In the drawing:

Fig. 1 is a longitudinal sectional view of the hydraulic door closer of this invention.

Fig. 2 is a sectional view along the lines 22 in Fig. 1.

Fig. 3 is a sectional view along the lines 3-3 in Fig. 1.

The door closer of this invention generally comprises a cylinder 10, a piston 12 movable within cylinder 10 and having associated therewith a piston rod 14 projecting from one end of the cylinder. The assembly is adapted to be mounted for operation by pivotally connecting the bracket 16, fixed to the end of rod 14, on the door jamb (not shown) adjacent the hinged edge of a door and by connecting the bracket 18 at the opposite end of the cylinder with the door (not shown) at a point removed from the hinged edge thereof.

Piston rod 14 is formed as a tubular member externally threaded at its outer end as at 20 for connection with bracket 16. The inner end of rod 14 is also threaded, as at 22, which end is adapted to threadedly receive an apertured end cap 24. A shaft 26 is arranged within tubular piston rod 14. At its inner end, shaft 26 has an end portion 28 of reduced diameter which provides a clearance space 30 between the outer surface of the end portion 28 and the inner surface of tubular piston rod 14. The extreme end of reduced portion 28 is threaded, as at 32, for engagement with the threaded hole 34 in end cap 24. The threaded portion 32 is fashioned with a V-shaped groove 36 which tapers inwardly towards the axis of the end portion 32 in a direc tion towards the inner free end of shaft 26 so that the groove 36 progressively decreases in cross section in a direction from left to right, as viewed in Fig. 1. The opposite end of shaft 20 is formed with a non-circular stub 38 which is adapted to be engaged by a wrench or the like for turning shaft 26 and thereby threading the shaft inwardly or outwardly of end cap 24 to increase or decrease the effective size of the bleeding orifice 40 formed by cooperation of the V-shaped groove 36 and the end face 42 of end cap 24. Shaft 20 is sealed with respect to tubular rod 14 by means of a conventional 0 ring 44 seated within a peripheral groove 46 formed on the larger diameter portion of shaft 26.

Piston 12 is slidably arranged on rod 14 and is generally U shaped so that it has an annular flange 48 seated on the outer surface of rod 14 and an annular flange 50 which slidably engages the inner cylindrical surface of cylinder 10. The radial flange portion 52 of piston 12 is fashioned with a plurality of circumferentially extending apertures 54. Apertures 54 are normally closed by a check valve 56 in the form of a disc having a flange portion 58 slidably arranged on the flange portion 48 of piston 12. A light spring 60 acts between check valve 56 and a washer 62 fixed on rod 14 to normally bias valve 56 to a position overlying and closing openings 54. Rod 14 is provided with apertures 64 through the wall thereof which establish communication between the opposite sides of piston 12 through orifice 40 when check valve 56 is closed. Rod 14 and piston 12 are biased in the direction inwardly of cylinder 10 by a coiled compression spring 66 acting between piston 12 and the end of cylinder 10. Spring 66 urges piston 12 on rod 14 to a position wherein the piston abuts against the inner end face of cap 24.

It will be observed that in the arrangement thus far described, when piston rod 14 is moved axially outwardly of cylinder 10, such as when the door is opened, piston 12 moves with it in a direction from left to right, and the fluid within cylinder 10 on the right-hand side of piston 12 causes check valve 56 to open and flows freely through apertures 54 into the portion of the cylinder on the other side of piston 12. Spring 66 is thereby compressed, and when the force acting on piston rod 14 and tending to pull it outwardly of cylinder 10 is released, spring 66 urges piston 12 in a direction from right to left thereby causing check valve 56 to close apertures 54 under the influence of spring 69. The hydraulic fluid within cylinder 10 on the left-hand side of piston 12 is thereby caused to flow at a slower rate through the groove 36, through bleeding orifice 40 into the clearance space 30 and back into the portion of the cylinder on the right-hand side of piston 12 through apertures 64. The action of spring 66 and of bleeding orifice 40 thereby effect a closing of the door at a slow controlled rate.

It will be observed that, per increment of longitudinal movement, as piston 12 and piston rod 14 move outwardly of cylinder 1!), that is, in a direction from left to right, the volume of the cylinder on the right-hand side of piston 12 is decreased considerably less than the voltime on the left-hand side of piston 12 is increased. On

the other hand, when the piston rod assembly moves in a direction from right to left, per increment of longitudinal movement, the volume on the left-hand side of piston 12 is increased an amount much greater than the volume of the cylinder 0n the right-hand side of piston 12 is decreased. These uneven changes in volume are, of course, due to the volume displaced by piston rod 14 on the righthand side of piston 12.

One of the features of the present invention is the provision of means within the cylinder 10 for compensating for the different rates in the changes in volume of the cylinder on the opposite sides of piston 12. These means are preferably in the form of a diaphragm 68 which is arranged to move and thereby increase and decrease the effective volume of cylinder it on the tleft hand side of piston 12. Diaphragm 63 has its edges secured between a flange 70 threaded on one end of cylinder 1t and the end face of an end cap member 72. The opposite end of cylinder 19 is also provided with a threaded flange "4 on which is secured an end cap member 76. A gasket 78 provides a sealed connection between flange 74 and member 76, the latter being provided with a removable plug $6 for filling the cylinder with hydraulic fluid. The outer cylinder surface of rod 14 is engaged by an O ring 82 in end cap 76 to provide a seal therebetween.

Diaphragm 68 may be formed of a fabric material treated to render it impervious to and unaffected by the hydraulic fluid within the cylinder. This diaphragm is flexible. At the center portion thereof a pair of opposed cup members 84 are secured thereto as by a rivet 36, and a spring 38 is positioned within end cap 72 with one end seated in the cup 3-; on one side of diaphragm 68 and with the other end seated in a similar cup 99 secured to the end Wall of cap member 72. Spring 88 normally tends to move diaphragm 68 in a direction from left to right and is resisted by the pressure of the fluid in cylinder 1t) between piston 12 and diaphragm 68.

it will be observed that diaphragm 6$ is in the nature of a wall of the cylinder which is movable in response to the pressure on the one side of piston 12 to vary the effective size of that portion of the cylinder on the lastmentioned side of piston 12. it will be appreciated therefore that means other than the spring-biased diaphragm 68 may be employed for varying the volume of the cylinder in this manner. The provision of a diaphragm 68 as 4 described is preferred, however, since it is economical from the standpoint of manufacture and presents no problems with respect to sealing.

By providing the movable diaphragm 68, it will be noted that the fluid system of our door closer is never subjected to any excessively high pressure. As the piston 12 and rod 14 move in a direction outwardly of the cylinder, that is, from left to right, the volume of fluid displaced from the right-hand side of piston 12 is less than the normal increase in volume on the left-hand side of piston 12. This would normally tend to create a vacuum on the left-hand side of piston 12 and an excessive pressure on the right-hand side of the piston. However, under'such conditions, diaphragm 68 moves in a direction from left to right and the pressures on the opposite sides of piston 12 are thereby balanced. When piston 12 and rod 14 move in a direction from right to left such as upon closing of the door, the volume of fluid displaced from the left-hand side of piston 12 would normally tend to be greater than the increase in volume on the right-hand side of piston 12 due to said movement. Under such circumstances, the pressure on the left-hand side of piston 12 would tend to rise to an excessively high value. However, under such circumstances, the build up of excessive pressure is prevented because, as thepressure rises on the left-hand side of piston 12, the fluid acts on diaphragm 68 to move the diaphragm in a direction from right to left and-thereby increase the effective volume of the cylinder on the left-hand side of piston 12.

It will thus be seen that with this arrangement the pressure of the hydraulic fluid in our door closer is maintained at a relatively low value under all conditions of operation of the door closer. Furthermore, it will be appreciated that the provision of means such as diaphragm 68 for compensating for the difierent rates at which volume of the cylinder changes on the two sides of the piston is a relatively inexpensive solution to the problem of leakage and does not add appreciably to the cost of the door closer. This is very important, since door closers of this type must be capable of being manufactored inexpensively, since they are used for controlling such light-weight doors as screen doors and storm doors. We have therefore provided 'a'door closer which is not apt to leak hydraulic fluid by incorporating in the hydraulic system an inexpensive device for balancing the pressures on opposite sides of the movable piston within the cylinder of the door closer. Excessively high pressures are not developed and the seals may therefore be of the inexpensive type customarily used for relatively low pressure applications. The cushioning eifect of diaphragm 68 is also assisted by the fact that piston 12 is 12 slidable on rod 14. If, for example, the door is subjected to a closing pressure in excess of that produced by spring 66 the piston rod will slide inwardlyof the cylinder while piston 12 will move in accordance with the rate at which the fluid bleeds through orifice 40.

The arrangement of the groove 40 and end cap 24' could be utilized even in a pneumatic closer. ,With a pneumatic closer, the adjustable orifice for bleeding air from the chamber on the left of the piston could be adjusted to produce a relatively rapid initial closing and a slow closing of the door near the end of its stroke. The orifice could be adjusted to produce the desired rate of closing of the. door during its final stages of closing movement. The diaphragm 68 would absorb the normally high pressure otherwise developed during the initial stages of movement when the air is compressed by reason of the action of spring 66 on the piston.

We claim:

1. A door closer comprising a cylinder having an end wall, a piston movable axially within said cylinder and having a piston rod connected therewith, said piston rod projecting axially outwardly through said end wall, valve means for permitting hydraulic'fluid to flow from one side ofthe piston to the other at a restricted rate as the mentioned end wall being movable generally axially of the cylinder to increase and decrease the effective volume of the cylinder between said piston and said last mentioned end wall.

2. The combination set forth in claim 1 wherein said last mentioned end wall comprises a flexible diaphragm.

3. The combination set forth in claim 2 wherein said diaphragm is normally biased to move in a direction towards said piston.

4. A fluid operated door closer comprising a cylinder closed at one end and having an annular flange member at its other end, a cup-shaped member secured to said annular flange member, a diaphragm closing said last mentioned end of said cylinder and having its peripheral edge portion secured between the faces of said cup member and said annular flange on said cylinder, said diaphragm being flexible and movable into the space defined by said cup member to increase the effective size of said cylinder, a piston movable axially within said cylinder and having a piston rod connected thereto, said piston rod projecting axially through the first mentioned end of said cylinder, valve means for permitting the fluid on one side of the piston to flow to the opposite side of the piston at a restricted rate when the piston is moved axially of the cylinder in a direction towards said diaphragm and check valve means for permitting free fluid flow across the piston when the piston moves axially away from said diaphragm.

5. The combination set forth in claim 4 including a spring within said cup member and acting against said diaphragm to bias the diaphragm in a direction outwardly of said cup member and towards said piston.

6. The combination set forth in claim 4- including a spring member acting on said piston and biasing said piston to move in a direction towards said diaphragm and a second spring member in said cup and acting on said diaphragm to move said diaphragm in a direction towards said piston.

7. A door closer comprising a cylinder, a piston movable axially in said cylinder, a piston rod connected with said piston and projecting outwardly through one end wall of said cylinder, said piston rod being of tubular shape and having an aperture therein communicating between the inside of the piston rod and the portion of said cylinder between said piston and said end wall, plug means extending axially through said piston rod and sealing the outer end thereof, said plug means having a threaded connection with said piston rod whereby the plug means may be advanced or retracted axially in said piston rod, the inner end portion of said plug means having a close fit with the inner end portion of said piston rod, said plug means having a portion adjacent and spaced outwardly from said inner end portion which is spaced from the inner surface of said piston rod and definin a chamber communicating with said aperture, said inner end portion of said plug means having an axial groove on the surface thereof which cooperates with said closely fitting portion of said piston rod to define a passage thruogh which fluid may pass from one side of said piston to the other, said groove increasing in cross section towards the inner end of said plug means.

8. The combination set forth in claim 7 wherein said plug means comprises a shaft, said shaft having its inner end threadedly engaged with the inner end of said piston red, the inner end portion of said shaft being of reduced cross section.

9. The combination set forth in claim 8 including a cap member at the inner end of said piston rod, said shaft having its inner end thre'adedly engaged with said cap member.

10. The combination set forth in claim 8 wherein said shaft is provided at its outer end with means for facilitating turning of the shaft within said piston rod.

11. A door closer comprising a cylinder having an end wall, a piston movable axially within said cylinder and having a piston rod connected therewith, said piston rod projecting axially outwardly through said end wall, said piston being slidably mounted on said piston rod, means biasing said piston toward the inner end of said rod, valve means for permitting hydraulic fluid to flow from one side of the piston to the other at a restricted rate as the piston is moved axially of the cylinder in one direction, check valve means for permitting free flow of fluid across the piston when the piston is moved axially in the opposite direction, said cylinder having an end wall at the end thereof opposite said first mentioned end wall, said last mentioned end wall being movable generally axially of the cylinder to increase and decrease the effective volume of the cylinder between said piston and said last mentioned end wall. 

